The advent of the Internet and the widespread popularity of personal computers have created an unprecedented demand for high bandwidth networks. Generally, Internet applications, from simple email to real time video conferencing, from web surfing to interactive movies, from interactive games to virtual TV stations, from online trading to online gambling, demand a higher bandwidth communication network. A fundamental challenge for the communication industry is to provide a reliable and affordable high bandwidth communication link to all types of Internet users. Various competing wire-line, wireless, and optical broadband technologies are deployed to partially meet the ever-increasing demand for higher bandwidth. The fastest growing broadband technology is the Digital Subscriber Line (DSL) technology, which provides a high bandwidth always-on connection over standard twisted pair copper media of the conventional telephone network. Among other wire-line media, coaxial cables are capable of providing always-on connections, however, its presence is insignificant compared to millions and millions of wired telephone customers who are connected by a twisted pair of copper wires. Other technologies, such as satellite, wireless, and optical, either provide limited coverage, limited bandwidth, or are too expensive for deployment to individual customers. As a result, DSL technology is uniquely positioned to provide the broadband link between individual customer premise and the central office, the so-called last-mile of the high-bandwidth communication network.
DSL is the fastest growing among emerging broadband technologies for very good reasons. First of all, DSL utilizes the existing copper wire network infrastructure. Secondly, compared to the voice modems, such as V.34 and V.90, used in most personal computers that provide up to 56 kbps dial-up connection, DSL provides a high bandwidth always-on connection with typical connection speeds from 384 kbps to 6 Mbps. Moreover, DSL is affordable with easy installation, simple turn-up, and high service reliability. The successful deployment of DSL is capable of providing digital broadband connection to anyone with an analog telephone line.
DSL services have been standardized over time by regional organizations such as, American National Standard Institute (ANSI), European Telecommunication Standard Institute (ETSI), and by world telecommunication organization International Telecommunication Union (ITU). These DSL standards define data communication protocols to connect customer premise equipment (CPE) to the central office (CO) and to provide connections to various networks, such as DSL service providers, virtual private networks (VPN), or the Internet. Various forms of digital data (e.g., voice, video, and data) can be transported using DSL technology. For transport of voice, DSL equipment is connected to the public switched telephone network (PSTN). For transport of video and data, DSL equipment uses the Internet via an Internet service provider (ISP). Voice over DSL (VoDSL) is capable of providing computer-to-computer, computer-to-telephone, and telephone-to-telephone voice services using an integrated access device (IAD). Video over DSL includes transport of MPEG-1 or MPEG-2 files, video conferencing using Internet Protocol (IP) standard such as ITU H.323, WebCam, and video mail. In addition, DSL supports simple data transport, e.g., bearer services, for virtual private network (VPN), leased data line such as T1 and E1, Point-to-Point Protocol (PPP), Asynchronous transfer mode (ATM), and Internet Protocol (IP).
Like other communication technologies, DSL has gone though a major evolution over the last decade and a collection of technologies, commonly referred to as xDSL, are developed under the umbrella of DSL. One type of subscriber loop digital transmission technology involves an integrated services digital network (ISDN), which has replaced a significant portion of the analog phone lines in Europe and Japan. ISDN offers integrated voice and data services and connection speed up to 144 kbps. Due to the high cost of deployment, an alternative solution called integrated digital loop carrier (IDLC) has been deployed in United States. However, resulting data rates were considered inadequate for individual customers. As a result, advanced DSL technologies were developed, which include HDSL, SDSL, ADSL, HDSL2, SHDSL, and VDSL, all of which are capable of connection speed in excess of 1 Mbps. These advanced DSL technologies were developed to address different needs and application demands, while serving different market segments. For example, SHDSL is a symmetric service designed for long reach office applications with connection speed of 1.5 Mbps, whereas, VDSL is designed to provide a very high-speed asymmetric service for a short-range applications.
SHDSL is a wire line Digital Subscriber Line (DSL) transmission technology that is designed to accommodate the need for higher data rates in telecommunication access networks. In particular, SHDSL supports duplex transmission of symmetric data rates over mixed gauge two-wire twisted metallic pairs, as described in the International Telecommunication Union (ITU) standard G.992.1—“Asymmetric Digital Subscriber Line (ADSL) Transceivers”, the body of which is incorporated herein by reference.
These and other drawbacks exist with current technologies.